Pneumatic tool with integrated electricity generator

ABSTRACT

A rotor for a pneumatic tool having electricity-generating capabilities comprises a shaft and an integral rotor body. The rotor body includes recesses dimensioned to receive an insulated subassembly comprising a magnet received within a nonmagnetic insulator. The nonmagnetic insulator acts to allow flux to be concentrated against stator windings. The improved rotor can be fitted with the insulated subassemblies in order to cooperate with a stator in the tool to generate electricity upon rotation of the rotor when pressurized fluid is applied to the vanes. A ring stator is supportable by a nonmagnetic end plate of the pneumatic tool, is disposed between the rotor and the rotor bearing and is preferably formed of Silicon Core Iron “B-FM” and magnet wire.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. national phase application claims priority of PCT applicationno. PCT/CA2005/000761 filed May 19, 2005, which claims priority to U.S.Pat. No. 7,095,142 issued on Aug. 22, 2006.

FIELD OF THE INVENTION

The following is directed in general to pneumatic tools with integratedelectricity generators, and more particularly to an integratedelectricity generator having insulated subassemblies embedded in itsrotor, and/or a compact stator supportable by the tool endplate.

BACKGROUND OF THE INVENTION

Conventional pneumatic tools, such as a pneumatic wrench, sander orgrinder, typically include a motor comprised of a rotor mounted on ballbearings supported by front and rear end plates, positioned on each endof a cylinder, for rotation of the rotor within the cylinder. The rotorand cylinder are non-concentrically aligned to provide a chamber alongthe length of one side of the rotor for receiving pressurized fluid. Themotor is further enclosed within the tool housing. The rotor is slottedlengthwise in a number of equidistant locations about its circumferenceto support vanes that radially slide in the slots enabling consistentcontact between the vane and the inside cylinder wall as the vanes enterand exit the chambered area. Each time a vane enters the chamber, itreceives a flow of pressurized fluid passing through the cylinder fromthe housing and thereby causing the rotor to rotate within the motor andtool housing. Gear teeth on the rotor's shaft transmit rotational forceto the working end of the tool.

U.S. Pat. No. 4,678,922 (Leininger) discloses a system for generatingelectricity using the flow of pressurized fluid such as air in apneumatic tool by way of a magnetic coupling between a speciallydesigned rotor and a stator. Magnetic means are affixed to the toolrotor, and thereby cooperate during rotation with a stator mounted inthe tool housing, motor cylinder or bearing end plate to induceelectrical current in the coils of the stator. The '922 disclosure thusprovides an integrated, self-contained and self-powered lighting sourcefor illuminating a workpiece. Various improvements have been made tointegrated electricity generators in order to improve their electricaloutput, longevity, usability and efficiency, and also to reduce theirsize. Examples of such improvements may be found in U.S. Pat. No.5,525,842 (also to Leininger) in which various configurations of rotor,stator and light supplies are introduced.

Rotors manufactured for use in conventional pneumatic tools aretypically machined from steel alloys as a single piece that can behardened to acceptable standards by heat-treating after machining.Hardening is generally required especially for the pinion area on therotor shaft because of the rigors undertaken by gear teeth during use ofthe tool. The drive gear and vane slots in a pneumatic tool rotor aretypically machined prior to heat treatment, while the metal isrelatively ductile.

When providing a conventional pneumatic tool such as an air tool withelectricity generation capabilities, a special rotor appended to anonmagnetic extension for housing magnets replaces the conventionalrotor. The nonmagnetic extension is used to help enhance polardistinction between north and south magnet orientations and to isolateor magnetically insulate magnets as much as possible from theferromagnetic influences of the steel rotor within the air chamber of asteel air cylinder, and any other magnetic influences in or outside thetool that could interfere with the focus of flux against statorwindings.

Because it is difficult to cut down a heat-treated rotor in order to addmagnets and a nonmagnetic extension (made of, for instance, nonmagneticzinc, 300 series stainless steel or aluminum), a special steel rotorhaving a shortened rotor body is turned, slotted, drilled, hobbed andheat treated and the nonmagnetic extension and magnets are subsequentlyappended to the rotor body. In an alternative method, a new shaft ismachined and heat treated, and subsequently received by a new andnonmagnetic rotor body in which magnets may themselves be received.

As would be understood by one of ordinary skill in the art, machining aspecial rotor in order to accommodate magnets for inducing electricityin a stator can be complex, time-consuming and accordingly expensive.Furthermore, a manufacturer intent on providing both conventional andelectricity-generating models of a particular pneumatic tool must planfor very different methods of manufacture of corresponding rotors.

Conventional pneumatic tools offered by various manufacturers havevarying proprietary sizes, shapes, tolerances, operation parameters andthe like. As such, each manufacturers' tool also requires a uniquestator to generate electricity efficiently and effectively for thattool. Furthermore, pneumatic tools having electricity generatingcapabilities typically require different magnet-side end plates fromtheir conventional counterparts because of the need to accommodate thesize and shape of stator coils and possible supporting circuitry. Inaddition, size and shape of the tool itself place constraints on thenumber of windings used for stator coils, the physical placement ofsupporting circuitry, and location of a pathway for directing generatedelectricity to its intended load. As would be understood, stator corepermeability, size of coils and amount of magnetic interference eachfactor into the amount of EMF produced by a generator, whileconsiderations such as component cost, manufacturability and degree ofvariation from a conventional counterpart all contribute to the overallcost of the tool.

Thus, improvements in the manufacturability of tools incorporating suchelectricity generators are sought.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, a rotor body for anintegrated pneumatic motor generator has formed therein recesses. Therecesses receive an insulated subassembly, which comprises a magnetwithin a nonmagnetic insulator, whereby the magnet is substantiallymagnetically insulated or isolated from the rotor body by thenonmagnetic insulator. Because the rotor only requires a number ofrecesses to be formed in its rotor body to receive the subassemblies, itrequires little additional machining over a conventional pneumatic toolcounterpart.

According to a further aspect of the invention, a ring stator is formedof a flat annular substrate having poles projecting therefrom, whereincoils are centered on the poles and connected to a connector. The ringstator is dimensioned to be placed between a rotor and the rotor bearingsuch that flux is directed towards the coils at least in part by thebearing.

According to a still further aspect of the invention, a nonmagnetic endplate for supporting a ring stator comprises an annular end walldimensioned to receive a rotor shaft and an annular side wall dependingfrom the end wall and dimensioned to support the ring stator. Theannular side wall has formed therein a slot for accommodating aconnector from the ring stator to a load, and cavities for accommodatingcoils of the ring stator. The ring stator may be placed within the endplate such that its coils cooperate with magnets on a rotating rotor togenerate electricity.

According to yet another aspect of the invention, a stator forcooperating with a rotor in an integrated electricity generator for apneumatic tool is provided. The stator comprises a substrate foraccommodating a shaft of the rotor; at least one induction pole, each ofthe at least one induction pole depending from the substrate and havingmounted thereon a respective coil; and an output connector fortransferring generated electricity from the at least one coil when saidrotor rotates relative to said stator.

According to another aspect of the invention, a stator for cooperatingwith a rotor in an integrated electricity generator for a pneumatic toolis provided. The stator comprises a disc dimensioned to cooperate with ashaft of said rotor; at least one induction pole, each of said at leastone induction pole depending from said disk and having mounted thereon arespective coil; and an output connector for transferring generatedelectricity from the at least one coil to a load.

These together with other aspects and advantages, which will besubsequently apparent, reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the preferred embodiment is set forth indetail below, with reference to the following drawings, in which:

FIG. 1 is a perspective view of a conventional pneumatic tool rotor;

FIG. 2 a is an end view of a replacement rotor according to the priorart to couple with a nonmagnetic extension and rotor magnets;

FIG. 2 b is a side sectional exploded view of the replacement rotor ofFIG. 2 a, taken along the lines A-A;

FIG. 2 c is a side sectional view of the assembled replacement rotor ofFIG. 2 a, taken along the lines A-A;

FIG. 3 a is an end view of an pneumatic tool rotor having a nonmagneticrotor body and a steel shaft, according to the prior art;

FIG. 3 b is a side sectional exploded view of the rotor of FIG. 3 a,taken along the lines A-A;

FIG. 3 c is a side sectional view of the rotor of FIG. 3 a, taken alongthe lines A-A, showing the placement of a magnet with respect thereto;

FIG. 4 a is an isometric exploded view of a magnet subassembly accordingto an embodiment of the present invention;

FIG. 4 b is an end isometric exploded view of a rotor showing anassembled insulated subassembly according to an embodiment of thepresent invention;

FIG. 4 c is a side sectional view of the rotor of 4 b showing associatedmagnetic flux map with concentrated flux density in the region of thestator at a face of the rotor body according to an embodiment of thepresent invention;

FIG. 5 is an isometric exploded view of the relationship between an endplate, a rotor bearing, the ring stator and its supporting circuit;

FIG. 6 is an isometric view of the ring stator, according to anembodiment of the present invention;

FIG. 7 is an isometric view of an end plate for a conventional pneumatictool;

FIG. 8 a is an isometric view of an end plate for supporting a ringstator, according to an embodiment of the present invention;

FIG. 8 b is an isometric view of the end plate of FIG. 8 a, supportingthe ring stator;

FIG. 9 a is an elevational exploded view of the rotor, end plate,bearing, a rotor extension and a disc stator according to an alternateembodiment of the invention;

FIG. 9 b is an alternate view of the end plate of FIG. 9 a;

FIG. 9 c is an alternate view of the rotor extension and disc stator ofFIG. 9 a; and

FIG. 9 d is a composed view of the components shown exploded in FIG. 9a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A conventional pneumatic tool is comprised of a casing onto which isconnected a fluid hose. The fluid hose conducts compressed fluid, suchas air, from a source through the casing of the tool, causing a rotorwithin the motor housed by the casing to rotate by effecting force onvanes on the rotor. The rotor, in turn, causes force to be transmittedfrom a pinion on the rotor through planetary gearing, to drive a ratchetof a wrench, abrasive disk of a grinder etc. at a working end of thetool. While some pneumatic tools make use of gearing in order totransmit rotational force to the working end of the tool, others do sosimply by employing a threaded shaft and a collet, or other meansappropriate to the primary application of the tool.

FIG. 1 is a perspective view of a rotor 10 for a conventional pneumatictool. Rotor 10 comprises a shaft 12 upon which is affixed a rotor body14. Shaft 12 has formed therein gear teeth 13 for enabling shaft 12 totransmit rotational force through gears to the working end of the tool,which may comprise a ratchet of a wrench, abrasive disk of a grinderetc. Rotor body 14 and shaft 12 are typically cast or machined from barstock as a single unit, but may be designed as an assemblage of morethan one part requiring additional assembly operations to finalize thecomponent. Rotor body 14 has formed therein a plurality of slots 16 forreceiving vanes (not shown), which, during operation, catch fluidflowing through the air cylinder chamber of the tool, causing rotor 10to rotate. Rotor 10 may be formed by casting or pressed powdered metal(PPM) with finishing by machine to attain required tolerance, screw orCNC machining from bar stock, or a combination of methods, using forinstance heat-treatable steel. Two grades of heat-treatable steelswidely used for high-grade rotors in pneumatic tools made by machinemethods are the AISI 41L40 and 4140 grades.

As would be understood by one of ordinary skill in the art, themechanical properties of rotors depend not only on the material used,but on a number of heat-treating factors which include sequence oftemperature changes, time of retention at certain temperatures and rateof cooling therefrom.

A pneumatic tool having electricity-generating capabilities is similarin operation to a conventional pneumatic tool. However, some componentsare either replaced, modified or added to take advantage of the relativemovement between the rotor and the stationary elements of the air motoror tool casing in order to generate electricity. Magnets mounted on thetool's rotor cooperate during rotation under influence of compressedfluid flow with coils of a stator mounted within the cylinder or endplate of the motor, or tool casing to generate electricity in the statorcoils. Because of the component replacements, modifications andadditions (to be described hereafter), tools havingelectricity-generating capabilities have been known to be somewhatdifferent in construction from their conventional counterparts.

FIG. 2 a is an end view of a known rotor 10 for an electricitygenerating pneumatic tool. Rotor 10 of FIG. 2 a is similar to that shownin FIG. 1, except it has been created to fit within the pneumatic toolmotor while also coupling with nonmagnetic extension 18 and rotormagnets 20. Rotor magnets 20 of rotor 10 cooperate with coils of astator (not shown) that is mounted within the ball bearing retaining endplate on a side of the cylinder of the motor within the tool, to produceelectricity during movement of rotor 10 relative to the stator housed bythe end plate. FIG. 2 b is a side sectional exploded view of the rotor10 of FIG. 2 a, taken along the lines A-A. Rotor body 14 of rotor 10 inFIG. 2 b is shorter than the rotor body in FIG. 1, so as to accommodatethe additional thickness of appended nonmagnetic extension 18, whilestill fitting within the motor and casing of the pneumatic tool.Nonmagnetic extension 18 receives magnets 20, is pressed and cemented torotor body 14, checked for tolerance and machined finished accordingly.FIG. 2 c is a side sectional view of the assembled rotor 10 of FIG. 2 a,taken along the lines A-A. As would be understood by one of ordinaryskill in the art, the process of forming an entirely unique rotor 10 andnonmagnetic extension 18, affixing the two and ensuring the assemblyfits within the required tolerances of the motor is a complexundertaking involving additional operations to manufacture over that ofa conventional rotor.

FIGS. 3 a-c show a different pneumatic tool rotor 10 having anonmagnetic rotor body 24 and a steel shaft 12, according to the priorart. The rotor body 24 is machined out of 7075 high tensile strengthaluminum—a light weight, nonmagnetic material that can be heat treatedto improve strength. Rotor body 24 of 7075 can further be hardcoatanodized with Teflon (trade mark), a known chemical lubricant, in orderto improve wear resistance to the sliding air vane regions. Shaft 12 isturned and hobbed out of a harder material, such as shaft gradeheat-treatable steel, because gear teeth 13 must withstand a great dealof wear relative to rotor body 24. Rotor body 24 must only typicallyaccommodate sliding vanes made of, for instance, conventional canvasreinforced, oil impregnated phenolic plastic or one of theNylon/Kevlar/Teflon composites. Shaft 12 is press fit into nonmagneticrotor body 24 and affixed using a two-part catalytic structuraladhesive. The nonmagnetic rotor body 24 fixedly receives magnets 20therein. While the hybrid rotor 10 shown in FIGS. 3 a-c can beadvantageously light due to the extensive use of 7075 aluminum, theprocess of forming an entirely unique rotor that accommodates magnets 20is a complex procedure. A rotor body and separate shaft must be formedand then affixed, the latter of which is a specialized operationrequiring additional fixturing and demanding rigorous adherence tospecified tolerance as major requirements.

It is well understood that no known material can actually fully insulateor obstruct magnetic flux. As such, use herein of the term “insulate” orderivations thereof is intended to mean, substantially, “to cause to bein a detached or isolated position” from direct contact with surroundingmaterial, much as would be understood by the word “isolate”.

With reference to FIGS. 4 a and 4 b, a rotor 10 for use in theintegrated electricity generator of the present invention also comprisesa rotor body 14 and a shaft 12. However, rotor body 14 contains aplurality of recesses 26 for receiving a respective insulatedsubassembly 19 that comprises a magnet 20 received by a nonmagneticinsulator 22. It can be seen that a conventional pneumatic tool rotor 10may be used in conjunction with insulated subassembly 19 becauseinsulated subassembly 19 is dimensioned to fit within recess 26, ratherthan project in front of rotor 10 as in the configurations of FIGS. 2and 3. Magnet 20 in FIGS. 4 a and 4 b is substantially cylindrical, butmachined slightly to have a flat side. This flat side is beneficial forenabling an adhesive to surround magnet 20 when magnet 20 is beinginserted into nonmagnetic insulator 22, thereby improving andsimplifying adhesion. Similarly, nonmagnetic insulator 22 has a flatside for enabling an adhesive for affixing insulated subassembly 19 torecess 26 of rotor body 14.

Each magnet 20 is preferably formed of sintered Neodymium (NdFeB), butmay be formed of Samarium Cobalt (SmCo). NdFeB and SmCo are known asrare earth magnets, which are presently some of the most powerfulpermanent magnetic materials commercially available. Furthermore, rareearth magnets are advantageously very difficult to demagnetize, makingthem very suitable for use in the vibration-intensive environment ofpneumatic tools. One drawback of the use of rare earth magnets is theirpotentially lower resistance to corrosion. To reduce the amount ofcontact by the moisture and air typical of, for instance, a compressedair stream, it is beneficial to coat the magnets prior to inserting theminto the insulated subassembly 19 by using a corrosion-resistantmaterial such as an epoxy, catalytic automotive epoxy sealant, zincchromate or epoxy-chromate. Alternatively, plating may be affected, suchas nickel electrodeposition.

Nonmagnetic insulator 22 may be formed of any suitable magneticallyinsulating material, such as nonmagnetic cast zinc, aluminum, brass orPPM 300 series stainless steel, in the form of a cup having a singleopen mouth in the direction of the front face of the rotor to enablemagnetic flux to be openly directed towards stator windings.

As can be seen, the present invention provides the advantage that amostly conventional pneumatic tool rotor may be used, that is onlyslightly modified by the creation of recesses each dimensioned toreceive an insulated subassembly. The recesses for the insulatedsubassemblies are relatively simple to form, even in a heat-treatedrotor using, for instance, a cobalt center cutting end mill or drillequivalent. Even in the case where rotors are only surface hardened, orinduction hardened in a focused area such as the pinion (and thus farless costly), the present invention provides a significant advantage.The use of insulated subassemblies for placement into easy-to-formrecesses on the rotor greatly reduces the amount that a conventionalpneumatic tool must be altered to generate electricity. Simply put, theonly alteration to a conventional rotor is the formation of recesses andthe insertion of the insulated subassemblies. This procedure is muchless costly in terms of time and complexity than the formation of arotor with a shortened body appended to a nonmagnetic extension, or theformation of a hybrid two-piece rotor, as described above.

Surprisingly, it has been found that the use of the nonmagneticinsulators as shown with respect to the magnets acts to beneficiallyfocus magnetic flux towards the stator windings. With reference to FIG.4 c, rotor 10 is shown with a superimposed representation of the fluxpattern 40 of magnets 20 when insulated subassemblies 19 are placedwithin recesses 26 of rotor 10. Residual magnetic flux is shown astypically absorbed by iron bearing material of rotor 10 at location 60.However, it can be seen that at location 50, where stator windings wouldbe positioned at 0.015 to 0.040 inch distance from face of rotor 10, theflux density is very concentrated. This flux density concentration isdue to the influence of the nonmagnetic insulators 22, which are made ofmagnetically insulating and non-flux absorbent material, as described.As would be understood by one of ordinary skill in the art, increasingthe concentration of flux density in this manner at location 50 adjacentthe stator assists greatly in increasing the amount of EMF generated inthe stator coils.

FIG. 5 is an exploded view of the relationship between a ring stator 70,a supporting circuit 79 and nonmagnetic air motor generator end plate 80and rotor bearing 90. Ring stator 70 and supporting circuit 79 arelinked by conductor 78. As can be seen, supporting circuit 79, mountedon a PCB board, includes diodes and a capacitor, and may includeadditional components for rectifying the generated electricity and forproviding storage of electricity for a period of time. Supportingcircuit 79 may also be mounted in other ways, such as on a Flat FlexibleCircuit.

It has been found that the compact Aerogel™ capacitors, known in the artof computer hardware, are extremely effective for temporarily storinggenerated electricity so as to provide more uniform EMF despitefluctuating rotor speed, even for a time after the rotor has stoppedrotating. It has been found through experimentation that there are asignificant number of conventional pneumatic tool designs that are able,due to size and/or shape constraints, to receive ring stator 70 andsupporting circuit 79 as separate units coupled by a wire or ribboncable conductor 78. By having separated supporting circuit 79 from ringstator 70, bearing 90 is able to be much closer to ring stator 70.Surprisingly, the close proximity of these two components actually actsto “flux-link” bearing 90 with ring stator 70 so as to improve theinduction of magnetic flux by ring stator 70. Therefore, by separatingthe ring stator 70 from supporting circuit 79, EMF that might be lostdue to size constraints may be at least partially regained.

Advantageously, due to its compact size, ring stator 70 can be disposedwithin end plate 80, between a rotor and rotor bearing 90, in order tobe as close as possible to a rotor. Supporting circuit 79 is preferablyencapsulated to form a solid state component in the form of a bearingcap or otherwise placed between a two-piece enclosure as showncomprising a bearing cap 92 and circuit cover 94 in order to keepcircuit 79 sufficiently separated from condensation that may travel withthe compressed air or other fluid passing through the tool. A groundconnection (not shown) appends from an edge of the PC board to makecontact with the conductive inner wall of the metallic end plate 80,completing the negative return path through the tool housing from thelighting appliance, made positive via connector 78 a from supportingcircuit 79.

An enlarged perspective view of ring stator 70 is shown in FIG. 6. Ringstator 70 is machined or compression molded from Free Machinable SiliconCore Iron “B” (otherwise known as Silicon Core Iron “B-FM”). SiliconCore Iron “B-FM” is a reasonably inexpensive material that has excellentpermeability permitting high flux density, and can be machined orcompression molded quickly. Induction poles 72 extend from annularsubstrate 71 and each have wrapped therearound coils 74 of magnet wire.In order to further reduce the “footprint” of ring stator 70, bobbins donot need to be used to form coils 74. Instead, magnet wire is wrappedaround induction poles 72 and glued, or otherwise encapsulated in form.When using a “bondable” magnet wire, coils 74 may be held to form simplyby applying a drop of denatured alcohol or acetone, which reacts withthe magnet wire insulator to create an adhesive. Further epoxy may benecessary to ensure coils 74 stay to form in the vibration-intensiveenvironment of an air tool. As would be understood by one of ordinaryskill in the art, coils 74 are linked in series—one end to circuitground 76 and the other to supporting circuit 79. Advantageously,because there are no bobbins, prior art inefficiencies due to absorptionof flux by bobbin flanges are eliminated.

FIG. 7 shows an enlarged perspective view of a prior art steel endplate. Turning now to FIG. 8 a, an improved nonmagnetic end plate 80 forsupporting ring stator 70 is shown, that is usable in both lighted andconventional pneumatic tools. End plate 80 is formed of aluminum oranother nonmagnetic material so that it does not unduly interfere withthe flow of flux between a rotor and ring stator 70, shown supported byend plate 80 in FIG. 8 b. End plate 80 accommodates ring stator 70 byvirtue of both a terminal slot 84 for connector 78 and sidewall cavities82 for clearance for coils 74. Terminal slot 84 aligns with the motorhousing thru-hole to provide access to the generated current fromoutside of the motor cavity. In addition, end plate 80 has areduced-thickness end wall 86 in order to decrease the magnetic gapbetween rotor magnets and induction poles 72 of ring stator 70. End wall86 also receives a shaft of a rotor by virtue of an opening formedtherethrough.

Conductors 78 and 78 a can be wire or ribbon cable, or a run within adiscrete single circuit comprised of Flat Flexible Circuit.

The many features and advantages of the invention are apparent from thedetailed specification and, thus, it is intended by the appended claimsto cover all such features and advantages of the invention that fallwithin the true spirit and scope of the invention. Further, sincenumerous modifications and changes will readily occur to those skilledin the art, it is not desired to limit the invention to the exactoperation illustrated and described, and accordingly all suitablemodifications and equivalents may be resorted to, falling within thepurpose and scope of the invention.

For example, while the preferred embodiment has been shown with fourinsulated subassemblies on one end of a rotor, it will be understoodthat any number of insulated subassemblies may be received by the rotor,dependent in part on the size of the insulated subassemblies, theconfiguration of the slots for receiving vanes with respect to the frontface of the rotor in which the insulated subassemblies are received andthat what ever the number of insulated subassemblies may be, that therebe an even number of magnetic poles disposed on the end of the rotor.

Furthermore, while the ring stator described above with is preferred dueto its inherent advantages, other stator configurations may be employed.For instance, with reference to FIGS. 9 a-9 d, a stator 112 is showndisposed on the opposite side of bearing 106 from rotor 100. Stator 112,having a plastic disc substrate (without an opening through it),comprises coils 114 each with a ferrous core. The coils 114 areconnected via connector 116 to a non-encapsulated supporting circuit(not shown) outside of the tool body (the supporting circuit would notbe exposed to the excessive condensation etc. in this case). Accordingto this embodiment, coils 114 are not linked by a ferrous “bridge” as inthe ring stator described above, but rather pressed into the plasticsubstrate. The ring core provides a magnetic “bridge” between coilsthereby maintaining in principle a closed circuit of magnetic flux forincreased output. For the embodiment shown in FIGS. 9 a-9 d, a simpleferrous flat bar or even a washer (not shown) placed across the backsideof the coils (opposite the poles facing the magnets) would increase thestator output. Also shown in FIGS. 9 a-9 d is an alternate embodiment ofa rotor 100, wherein an aluminum (nonmagnetic) extension 106 is threadedonto threaded shaft 102 of rotor 100. The extension 106 receives magnets110. It can be seen that different rotor configurations may be employedwith different stator configurations, as long as they interoperate togenerate electricity in the stator coils when the rotor and statorrotate relative to one another.

While Aerogel capacitors are preferred for use in the supporting circuitdue to their excellent performance, it would be understood that othercapacitors may be employed, such as electric double layer capacitors.

While aluminum has been described as the preferred material for the endplate, it will be understood that other materials, such as presspowdered/sintered stainless steel alloys may be employed also.

Furthermore, while the magnets, nonmagnetic insulators and rotorrecesses have been shown as generally cylindrical, it will be understoodthat these components may be of any configuration, shape or dimensionsufficient to impart magnetic flux against the inductors and hence coilwindings of a stator, as long as the relationship between the magnetsand the nonmagnetic insulators are such that the magnets are isolatedfrom substantially all but the stator, and embeddable therein.

While the nonmagnetic insulator has been shown in the form of a cup, thenonmagnetic insulator may be formed in the shape of a box, bowl,open-ended tube, triangular, or the like. It is sufficient that thenonmagnetic insulator receives a magnet, is receivable in acorresponding recess of the rotor, and acts to surround the magnet withnon flux-absorbent material in such a manner that flux is still directedtowards the inductors and coil windings of the stator.

While it is advantageous to make use of some of the strongest, mostdemagnetizing-resistant magnets commercially available such as NdFeB orSmCo for the rotor, it will be understood that the present inventionwould work using magnets of any magnetic material, albeit at the cost ofreduced induced EMF in the stator coils.

Furthermore, it is conceivable that a rotor having the recesses could beused in a conventional pneumatic tool, such that both the conventionalpneumatic tool and an electricity-generating counterpart use the exactsame rotor. In fact, it is common practice throughout both automotiveand industrial pneumatic tool industries for engineers to providerecessed rotors in pneumatic tool motors to decrease the amount ofmaterial used to create the rotor in both plastic injection molding andPPM rotor construction, and also to decrease the overall weight of thetool in the larger air tools. However, the formation of recessesdimensioned to receive the insulated subassemblies provides acombination of weight loss for conventional tools and simple conversionto electricity-generating capabilities, where the rotor is concerned.Manufacturing is thus greatly simplified.

While the above has been described with reference to a pneumatic toolhaving a primary function such as a sander, grinder or wrench, it is tobe understood that the present invention is applicable to tools havingother primary functions. One might also conceive of applications whereinthe primary function of the tool is to generate electricity for variousapplications.

1. A rotor for an integrated electricity generator of a pneumatic tool,said rotor comprising: a shaft comprising means for rotatably mountingsaid rotor within a tool housing of said pneumatic tool such that saidrotor rotates in response to a flow of pressurized fluid through saidtool; a ferrous rotor body integral with said shaft and having aplurality of recesses therein, each of said recesses receiving acorresponding subassembly that comprises a magnet received bynonmagnetic isolator that isolates the magnet from direct contact withthe surrounding ferrous material of the rotor body; wherein each of saidrecesses is positioned within said rotor body to enable the magnet ofsaid corresponding subassembly to cooperate with a stator of saidintegrated electricity generator to generate electrical current in saidstator upon rotation of said rotor within said tool housing.
 2. Therotor of claim 1, wherein each of said recesses is substantiallycylindrical.
 3. The rotor of claim 1, wherein each of said recesses isfurther dimensioned to receive an adhesive for affixing a correspondingsubassembly to said rotor body.
 4. The rotor of claim 1, wherein saidshaft further comprises means for transmitting rotational force to aworking end of said pneumatic tool.
 5. The rotor of claim 4, whereinsaid means for transmitting rotational force comprises gear teeth. 6.The rotor of claim 1, wherein said rotor body and elongate shaft arehardened by heat-treatment.
 7. A rotor assembly for cooperation with astator in a pneumatic motor generator integrated within a tool housingof a pneumatic tool for generating electrical energy, said rotorassembly comprising: a plurality of subassemblies, each of saidsubassemblies comprising a magnet received by a nonmagnetic isolator; ashaft for rotatably mounting said rotor assembly within said toolhousing; a ferrous rotor body integral with said shaft and havingrecesses for receiving a respective one of said subassemblies; whereinsaid nonmagnetic isolator is dimensioned to isolate the magnet fromdirect contact with the surrounding ferrous material of the rotor bodywhile permitting the magnet's flux to be exposed to said stator whensaid rotor is within said tool housing.
 8. The rotor assembly of claim7, wherein said nonmagnetic isolator is an aluminum cup and said magnetis a cylinder dimensioned to fit within said aluminum cup.
 9. The rotorassembly of claim 7, wherein said magnet is formed of sinteredNeodymium.
 10. The rotor assembly of claim 7, wherein said magnet isformed of Samarium Cobalt (SmCo).
 11. The rotor assembly of claim 7,wherein at least said magnet is coated with an epoxy.
 12. The rotorassembly of claim 7, wherein at least said magnet is plated with acorrosion resistant material.
 13. A rotor assembly for cooperating witha stator in an integrated electricity generator in a pneumatic tool, therotor assembly comprising: an elongate shaft comprising means forrotatably mounting said rotor in said pneumatic tool; a ferrous rotorbody integral with said shaft, said ferrous rotor body having at leastone slot, each of said at least one slot dimensioned to received acorresponding vane, said ferrous rotor body having a plurality ofrecesses on an end thereof, each of said recesses receiving acorresponding one of a plurality of subassemblies, each of saidplurality of subassemblies comprising: a magnet; a nonmagnetic isolatordimensioned to received said magnet and to isolate the magnet fromdirect contact with the surrounding ferrous material of the ferrousrotor body while permitting the magnet's flux to be exposed to saidstator.